This SLB method will map requests persistency with the same hostname to the same real service in the group.
slb group method <group_name> ph [rr|sr|lc] [threshold]
[rr|sr|lc] - argument can be called the "first choice method". If a client request does not yet have an
assigned real service, this method will be used to choose a real service for that client, based on
the request properties appropriate to the group method.
[threshold] - argument only applies if the "first choice method" is lc, and is the same as the group method lc threshold parameter.